春季中国西南降水与青藏高原及周边非绝热加热之间的关系

基于气象观测资料和再分析资料，从西南地区降水年际变化规律入手，运用统计学方法从时空角度分析了与其相伴随的环流型和非绝热加热的关联。结果表明，当西南地区降水偏多时，东西向异常气旋、反气旋分别位于我国长江以南地区上空以及青藏高原西南侧上空对流层中、高层，西南地区对流层高层被异常偏北风控制，低层被异常偏南风控制，中层伴有较强的异常垂直上升运动，且与异常非绝热加热源区基本重合，而青藏高原西南侧上空对流层中层为异常的垂直下沉运动，且与异常非绝热加热汇区基本重合；反之亦然。在此基础上进一步运用气候动力学方法揭示了导致西南降水异常的可能物理过程：高原西南侧爬升流的异常垂直运动通过影响南支气流向下游的水汽输送异常，进而导致西南地区非绝热加热异常，最终实现对西南地区降水的调制作用。

The Relationship Between the Precipitation over Southwest China and the Diabatic Heating over Qinghai-Tibetan Plateau and Its Vicinity in Spring

With the meteorological observation data and reanalysis data set, the interannual variation of the precipitation over Southwest China and the anomalies of the accompanying circulations and diabatic heating were analyzed firstly using statistical methods. It is shown that, when the total of precipitation over Southwest China was more than normal, one dipole of cyclonic and anticyclonic atmospheric circulations along the east-west direction was located in the middle and upper troposphere over south of the Yangtze River and over southwest regions of the Qinghai-Tibetan Plateau respectively; over Southwest China, the anomalous northerly and southerly wind dominated the upper and lower troposphere respectively, and the anomalous diabatic heating source was lied in the regions where the anomalous ascending motion prevailed; the descending motion anomaly and the anomalous diabatic heating sink almost concurred in the middle troposphere over the southwest of the Qinghai-Tibetan Plateau. When the total of the precipitation over Southwest China was less than normal, the opposite is the case with the aforementioned. Furthermore, the dynamical diagnosis was used to reveal the possible physical process of the precipitation anomaly in Southwest China. That is, the abnormal ascent of one part of the South Branch to the southwest side of the Qinghai-Tibetan Plateau, by affecting the total amount of water vapor transport downstream and then the diabatic heating anomalies in Southwest China, eventually played a role in modulation of the precipitation in Southwest China.